The present invention relates generally to softball and baseball bats, and more particularly to such bats having a varying circumferential wall thickness.
In an effort to continually improve bats, manufacturers seek out new materials and designs. Most top of the line bats utilize the highest tensile and yield-strength alloys available, such as the 7000 series hard alloys, titanium and composites, all of which are readily available to manufacturers. Thus, in an effort to differentiate products constructed of the same materials, manufacturers and engineers focus on the development of features that will enhance the performance and durability of the bat. To this end, there have been several attempts to design bats which include structural features to maximize performance and/or reinforce the interior of the tube for increased durability.
One such attempt was disclosed in U.S. Pat. No. 5,364,095, assigned to Easton, Inc., which is incorporated by reference as if fully set forth herein, is directed to a tubular metal ball bat internally reinforced with fiber composite. The bat comprises a hollow metal tube including a metal sleeve compressively engaged with the interior of the tube. The sleeve is formed of carbon fibers in an epoxy matrix.
U.S. Pat. No. 5,511,777, issued to McNeely, which is incorporated by reference as if fully set forth herein, is directed to a ball bat with a rebound core. The McNeely bat comprises a hollow tube having a tube wall including a barrel portion, a tapered portion and a handle portion. The bat includes an inner damper that is covered by a resilient attenuator sleeve. The inner damper is inserted into the hollow tube such that the resilient attenuator sleeve is compressed between the inner damper and the tube wall. A cap covers the open top of the tube and a knob is installed to the open bottom.
U.S. Pat. No. 5,415,398, issued to Eggiman, which is incorporated by reference as if fully set forth herein, is directed to a softball bat having a tubular insert. A tubular aluminum bat frame is provided with a large diameter impact portion, an intermediate tapering portion, and a small-diameter handle portion. A tubular insert is suspended within the impact portion by interference fits at each insert end. A gap exists along the length of the suspended insert separating the insert from the interior of the impact portion. The gap is filled with grease to facilitate relative movement between the insert and the tubular frame when a ball is batted.
All of the aforementioned designs attempt to maximize the wall flexibility, or xe2x80x9ctrampoline effectxe2x80x9d, and/or reinforce the interior walls for durability. Furthermore, all of these designs utilize an interior reinforcing mechanism with an exterior tube of uniform wall thickness.
However, an important consideration in bat design is overall bat weight. Thus, it is desirable to design a bat of minimal weight, which is generally achieved by using a lightweight material and by minimizing the wall thickness of the bat, without compromising the structural integrity of the bat. In order to maintain the structural integrity of the bat upon impact, the wall thickness of the impact portion of the bat must be a certain thickness, which is based on the strength of the bat material. Previous bat designs have attempted to minimize bat weight by varying the wall thickness along the length of the bat. What is needed, then, is a bat that minimizes bat weight by varying the wall thickness circumferentially.
The bat of the present invention comprises a tubular body having a handle portion, a tapered mid-section and a barrel or impact portion. In order to increase the strength of the bat and yet optimize wall flex for maximum xe2x80x9ctrampoline effectxe2x80x9d, the wall thickness of the bat varies about the circumference. In one embodiment, the outer diameter of the bat is constant, while the inner diameter varies between a maximum diameter and a minimum diameter to create alternating points of maximum wall thickness and minimum wall thickness. In an alternate embodiment, the inner diameter of the bat remains constant, while the outer diameter varies to create alternating points of maximum and minimum wall thickness. The distance between points of maximum and minimum wall thickness is such that there are at least two points of maximum wall thickness under the impact area, i.e. the area of the bat that is contacted by a ball upon impact. Further, the minimum wall thickness is selected so that the average wall thickness under the area of impact does not fall below the thickness required to resist denting based on the strength of the particular material from which the bat is constructed.
The bat may be constructed from any suitable material, such as aluminum, titanium, composites and the like.
A first object of this invention is to provide a metal ball bat that is lightweight yet strong enough to resist ball impact damage.
It is an object of the present invention to provide a bat having a handle portion, a mid-section and a barrel portion with a wall thickness that varies circumferentially.
It is another object of the present invention to provide a bat having a variable circumferential wall thickness wherein there are at least two points of maximum wall thickness under any given impact area.
It is another object of the present invention to provide a bat having a variable circumferential wall thickness wherein the average wall thickness under a given impact area is no less than the minimum thickness required to resist denting for the particular bat material.
These and other objects, features and advantages shall become apparent after consideration of the description and drawings set forth herein. All such objects, features and advantages are contemplated to be within the scope of the present invention even though not specifically set forth herein.